Question

What would happen to the U.S. economy if all or most manufactures here made 80-85% of their own parts like SpaceX and Tesla?

Answer 1

The U.S economy won't fall, but it will have some problems.

Step-by-step explanation:

Now,

If all manufactures start making their own parts, the U.S Government wont have any customers to buy the resources needed to make a part. These Manufacturers will have to make mines and factories of their own to do this. It is unlikely that manufacturers will make factories or mines to make their own parts because it is going to be a huge project and its going to cost a lot of money which will be a lose-lose situation because both the U.S and the manufacturers are not going to benefit.